This invention relates generally to an improved apparatus for the hemming of two ductile flanged components. More specifically, this invention relates to the hemming of a catalytic converter and a heat shield.
In general, hemming may be utilized to join two components together, by forcing an angled flange of a first component over a flange of a second component. A crimped hem is formed by subsequently applying a pressure between the first bent flange and the second flange.
An apparatus and method to create a hem between a first component having a 90 degree flange and a second component having a straight flange is disclosed in U.S. Pat. No. 5,150,508 to St. Denis, issued Sep. 29, 1992. The apparatus uses a set of pre-hem dies for a pre-hemming operation to bend the 90 degree first component flange 45 degrees. A second set of final hem dies is utilized to complete the bending of the first component flange. This machine requires the use of three separate drive systems; a first drive system for the vertical movement of the components to be hemmed, a second drive system for the actuation of the pre-hem die set and a third drive system for the actuation of the final-hem die set. Additionally, this invention requires the components to be cycled up and down twice, first for engagement with the pre-hem die set and second with engagement with the final die set.
The two step apparatus and method for hemming two components requires the use of two presses and/or die sets, and the use of more than one drive system and cycle.
Canadian Patent No. 253,484 discloses a one-step hemming machine for car doors which combines the pre-hemming and final hemming operations into a single machine. In this machine, a die block is moved in a single stroke through a linkage mechanism. Similarly, Canadian Patent No. 701,558 discloses a one-step hemming machine for automobile doors in which a die block is rotatably moved in a single stroke through a linkage mechanism. In both of these machines, the components and supporting bed remain stationary during the hemming operation. However, it has been noted that these machines involve the requirement to accurately index the position of the die block. Additionally, the use of a single die block has a tendency to roll the flange edge of one of the components altering the dimensional integrity of the final assembly.
Consequently, it would be desirable to have a hemming apparatus and method that could create a crimped hem utilizing a single drive system that could be accomplished in one cycle while maintaining dimensional integrity of the final assembly.